Use of supercritical CO

1. A process for coating urea-containing granules with organic polymers, the process comprising:

compressing and condensing gaseous carbon dioxide to obtain liquid carbon dioxide, wherein the compressing of the gaseous carbon dioxide occurs in a first step in a low-pressure compression step and in a second step in a high-pressure compression step, wherein the low-pressure includes from 5 bar to 10 bar and the high-pressure includes from 20 bar to 35 bar;

increasing at least one of pressure or temperature above a critical point of carbon dioxide to obtain supercritical carbon dioxide;

dissolving an organic polymer in the supercritical carbon dioxide to obtain a polymer-containing solution; and

mixing the polymer-containing solution by at least one of spraying the polymer-containing solution onto or bringing the polymer-containing solution into contact with urea-containing granules, in which

a simultaneous or subsequent lowering of temperature and/or pressure below the critical point of carbon dioxide occurs, and

coated urea-containing granules and gaseous carbon dioxide are obtained.

2. The process of claim 1 wherein the organic polymer includes biodegradable polymers.

3. The process of claim 2 wherein the biodegradable polymer includes polylactides (PLA), polyglycols, polycaprolactones, poly(hydroxybutyric acid), poly(hydroxyvaleric acid), polyalkyl terephthalates, polyanhydrides, poly(1,4-dioxane-2,5-dione), polyamino acids, polysaccharides, cellulose esters, cellulose hydrate, cellulose acetate, carboxymethyl cellulose, lignin, polyhydroxy fatty acids, starch, biodegradable polyesters, biodegradable polyamides, biodegradable polyimides, polyhydroxyalkanoates and polybutylene succinates (PBS), amylose, amylopectin, and/or mixtures, oligomers, derivatives, and copolymers thereof.

4. The process of claim 1 wherein the polymer-containing solution contains between 20 to 70% by weight biodegradable polymers.

5. The process of claim 1 comprising returning the gaseous carbon dioxide to the compressing and condensing step and converting the gaseous carbon dioxide to supercritical carbon dioxide.

6. The process of claim 1 comprising providing the gaseous carbon dioxide and the supercritical carbon dioxide in a connected industrial plant complex.

7. The process of claim 1 wherein the condensation occurs with the aid of ammonia from a connected ammonia refrigerating system.

8. The process of claim 1 comprising subjecting the liquid carbon dioxide, after the compressing and condensing, to a flash process for at least one of removal or outgassing of inert, non-condensable gases.

9. The process of claim 1 wherein a cold/heat recovery and/or cooler are provided at least one of before the first step, between the first and second steps, or after the second step.

10. The process of claim 1 wherein the urea-containing granules and/or the coated urea-containing granules contain at least one of, nitrates, phosphates, potassium, calcium, or sulfur.

11. The process of claim 1 wherein the urea-containing granules have a mean particle size of 0.5 to 8 mm.

12. The process of claim 1 comprising mixing the polymer-containing solution with the urea-containing granules in one or more coaters with tangential spraying.

13. The process of claim 1 wherein the first and second compression steps occur within a first housing.